Page:Operation Crossroads 1946.pdf/374

 USS Nlaqara ( A P A - 8 7 ) 29 J u l y

USS O ' B r l e n ( 0 0 - 7 2 5 )

Frame No.

0826 The commanding officer and reboarding Teams A and B reboarded the ship and commenced inspection of it: no apparent damage was noted. 1535Underwaytoshiftberthsinthelagoon. 1601Anchoredinberth381. 1615 The remainder of crew returned on board with baggage and gear. Inspections conducted for evidence of radioactivity 0 . 4 R/24 adjacent to the ship's side revealed about hours. which decreased in intensity on board to a point 5 feet (1.5 meters) from the sides to 0.1 R/24 hours. The average reading of compartments below the waterline was 0.05 R/24 hours (Reference 2). Crew S l z e : 30 July

1 August Afternoon

2 August

3 August

4 August

5 nugust

51 68 82 93 107 110 122 135

Port 0.011 0.060 0.052 0.053 0.042 0.079 0.096 0.036

Starboard 0.012 0.048 0.024 0.018 0.072 0.072 0.048 0.012

USS O'BRIEN ( 0 0 - 7 2 5 ) 237

BlklnA l tolA l rrlval: 15 June 1946 All decks and bulkheads in compartments B l k l nA l t o lD l eparture: 8 August 1946 above the waterline were washed down with Shot ABLE L o c a t l o n : 4 3 nml (80 km) SW Shot BAKER L o c a t l o n 1: 2. 5 nml ( 2 3 km) W soap and water. The sides of the ship San F r a n c l s c o were also scraped to a distance of aboutO e c o n t a m l n a t l o Ln o c a t l o n : 5 feet (1.5 meters) below the waterline O p e r a t l o n aCl l e a r a n c e : 6 November 1946 F l n aCl l e a r a n c e : 19 December 1946 to remove marine growth. Task U n l ta n dF u n c t l o n

Underway and put to sea to wash the ship's sides.ThisreducedtheGeiger readings approximately40 percent. Speed increased to 15 knots (28 km/hr); however, this did not reduce the radioactivity further. Upon reentry into Bikini. hogging lines with scrapers attached were led around the ship and the to remove bottom scraped in an attempt some of the marine growth.

The destroyer O'Brien (DD-725) served in TG 1.1 (Surface Patrol), Destroyer Division 71. Before its arrival at Bikini, O'Brien had special oceanographic and radiological equipment installed aboard. It conducted radiological patrols. including monitoring the area just inside the lagoon ent rance. Shot ABLE ( 1 J u l y 0, 9 0 0 )

1 July

Monitor made inspection, finding the ship below 0.10 R/24 hours throughout. Maximum radioactivity on a portion of the ship's hull adjacent to gangway: reading there was 0.095 R/24 hours.about0.05 R/24 2 hours higher than the rest of the ship. Safe distance from Niaqara's hull reduced 1 foot 0.3 from 5 feet (1.5 meters) to meter). 3 Continuedtoscrapehull.Duringthis timetheentirebottomandwaterline area were scraped. 4 Niaqara was again inspected. At this time the monitors declared the ship radiologically safe on all parts and gave It the radsafe clearance required to depart from5 Bikini.

Steaming on course in accordance with JTF 1 Op Plan 1-46. Commenced radiological patrol. 1414 1815 Stopped all engines to obtain radiological data. 20 18 Laying to to collect radiological data.

July 0620 July

July

July 0210 0647 0742

Due to the position of Niaqara's anchorage, materials f r o m decontaminated ships were washed against it. To its sides the prevent these materials from clinging to 0938 waterline was washed down with firehoses each day for 1000 a week, and the bottom was periodically scraped. At the end of a week. another Geiger inspection showed a 9 July maximum of 0.082 R/24 hours at frame 68. The rest of 1306 the ship was below 0.018 R/24 hours (Reference 4 ). The results of one inspection showed the following (R/24 9-14 July hours) (Reference4 ) : 14 July Starboard No.Frame 0931 1410 14 0.036 0.042 28 0.054 0.018 15-22 July 42 0.024 0.015

369

Arrived on station: commenced patrolling station. At 0038, 0211, 0341, 1006, 1245, 1543, and 2134, laying to on station to obtain radiological data. At0151. 0623, 1005. 1221, 1446, 1835. 2054, and 2345 obtained radiological data on station. Took radiological data on station. Entered Bikini Lagoon. USS Enoree (AO-69). Moored portside to berth 30. Underway to anchorage. Anchored in berth 190 North. Bikini. Underway to depart lagoon. Took hydrographic data. Reentered Bikini Lagoon. Anchored in berth 910. Bikini. Collected radiological and hydrological data from Bikini and surrounding waters.